1. Technical Field
The present invention relates to a wireless communication apparatus and, particularly, is suitable for being applied to a method by which a carrier clock and a baseband clock used between wireless communication apparatuses are shared by wire between a transmission side and a reception side while being spread in spectrum.
2. Related Art
In a heretofore known wireless communication apparatus, there is a technology which, by replacing a wired connection using a flexible substrate and a connector with a wireless connection, realizes an improvement in reliability and mobility, a reduction in assembly cost, a securing of structural freedom, a maintenance facilitation, a reduction in size of a printed circuit board and the like.
Also, as a method for reducing an unnecessary radiation due to a clock, JP-A-2003-150143 discloses a method which, by changing an oscillation frequency itself by means of an FM modulation using a voltage controlled oscillator etc., spreads a clock spectrum and reduces a peak value of the clock spectrum.
In contrast, JP-A-2005-57544 proposes a technique which multiplies an M sequence by a clock in order to spread a spectrum in a wider spectrum space. In the technique, by multiplying the M sequence again at a receiving end of the clock, it is possible to reproduce a clock having no jitter.
However, in a wireless communication, when a frequency of a reference clock used to generate a carrier becomes high, an unnecessary radiated electromagnetic field increases, and there has been a problem in that, as well as it causing a significant impediment to other systems, official restrictions also preclude a product shipment.
Also, in the method disclosed in JP-A-2003-150143, as the oscillation frequency changes due to the FM modulation, a large clock jitter occurs, and there has been a problem in that it is difficult to use it as a Wireless communication carrier.
Also, in the method disclosed in JP-A-2005-57544, as the clock is reproduced from a spectrum spread signal, it is necessary to send an M-sequence signal simultaneously with the spectrum spread signal, and to provide a circuit for reproducing a symbol synchronization of the M-sequence signal, and there has been a problem of an increase in wiring space and circuit scale.